This pain at the pump threatens to drain some of the extra take-home pay that many households are enjoying from Trump's tax cuts.

Higher gas prices are on track to cost Americans an extra $38 billion in 2018, wiping out about one-third of the direct benefit from the tax law, according to Morgan Stanley. The firm estimated that American households will take home an additional $128 billion in 2018 because of the new tax law.

"While the tax cuts have lifted take-home pay for the vast majority of workers," Morgan Stanley chief US economist Ellen Zentner wrote to clients, "rising gasoline prices are eating into that benefit."

The jump in gas prices may not be done yet. Crude oil climbed nearly 3% on Tuesday and topped $71 a barrel for the first time since late 2014.

Trump's decision to exit the Iran nuclear agreement and re-impose sanctions on the OPEC nation could lift prices even higher. The key will be whether Iran's crude oil exports are significantly restricted — and whether Saudi Arabia or another nation fills the gap.

Strong demand and production cuts from OPEC and Russia tightened global oil supplies prior to the Iran decision.

Saudi Arabia pledged on Tuesday to "work with major producers within and outside OPEC" to "mitigate the impact" of supply shortages.

The United States may be able to compensate as well. US oil production is skyrocketing, though output in the oil-rich Permian Basin is being limited by pipeline shortages that could last until late 2019.

The US Treasury said oil sanctions on Iran won't take effect until November. However, Treasury officials advised nations to immediately cut back imports of Iranian crude.

Goldman Sachs said Brent oil prices could top its summer forecast of $82.50 a barrel, or about 7% higher than current prices.

"Oil prices will certainly move up," Fereidun Fesharaki, chairman of energy consulting firm FGE, wrote to clients on Wednesday. $90 or $100 oil "may again be in the cards," Fesharaki wrote.